Highway crossing gate



Nov. 5, 1940. w. K. HOWE ET AL HIGHWAY CROSSING GATE Filed Dec. 24, 1938INVENTORS Mgbflowe and JC-Lindner, TMTQNM' Patented Nov. 5, 1940 UNITEDSTATES PATENT OFFICE 2,220,154 HIGHWAY CROSSING GATE ApplicationDecember 24, 1938, Serial No. 247,624

18 Claims.

This invention relates to crossing gates for blocking highway trafllc ona highway intersecting a railroad, and more particularly to a crossinggate operated wholly electrically.

In the electrical operation of crossing gates, by reason of the lengthof such gates, certain problems are encountered that have not beenencountered in the electrical operation of semaphore blades for railwaysignalling purposes. One of the obstacles surrounding the economicoperation of crossing gates is due to the enormous wind resistanceoffered by gates of a length to extend across a highway, and also by theoccasional breakage of the gate arm. By reason of such wind resistancethe operation of the gate may be either aided or. retarded depending onthe direction of the wind. If the electricaloperation of the gate isretarded this effect may be compensated for by installing a higher gearratio gear train or by employing a larger motor. If, on the other hand,the direction of the wind is such as to aid the motor in moving the gatearm it is found necessary to add supplemental means for at timespreventing excessive speed of operation of the gate arm. The secondobstacle encountered when operating a crossing gate wholly electricallyis the variable and greatly increased forces that are encountered whenice and sleet accumulates on the gate or the gate arm is broken off, asfor instance by an automobile driving through the gate. This increasedforce when the gate is broken oil is due to the fact that the forceexerted by the counterweight of the gate is in a directionto move thegate to its clear position and this force is considerably in excess ofthe biasing force that existed in the opposite direction before the gatewas broken off. In other words, the crossing gate by reason of itslength is of considerable weight andin practice a counterweight ofconsiderable weight is added so that the biasing force of the gatetending to move it to its stop position is almost entirelycounterbalanced. If now the crossing gate is broken ofi, either due toexcessive loading as by ice or sleet, or by being'struck by anautomobile, the counterweight alone remains, as a result of which themechanism will be operated toward its clear position at a tremendousspeed unless specially restricted, thereby damaging same.

In accordance with the present invention it is proposed to employ ahighway crossing gate which is provided with a counterweight to almostneutralize the torque produced by thegate and to provide a motor andsuitable gearing for operating the gate to its clear vertical position,and to provide normally energized hold-clear mechanism for electricallyholding the gate in its clear position, which hold-clear mechanism isreleased when the clearing potential is removed. It is proposed toprovide a friction slip clutch or brake through the medium of which thehold-clear mechanism may retard the operation of the mechanism near theend of its clearing stroke and hold the gate against movementthereafter, and to provide electro-dynamic braking means to retard theoperation of the crossing gate in its gravitational movement from theclear to the stop position, and to so construct the electrodynamicbraking means that it will also function when the motor runs idle towardits clear position. To provide additional means effective to afford asnubbing circuit to electrodynamically brake the motor more effectivelywhen excessive forces are encountered as when the counterweight ismoving from the stop to the clear position due to the gate arm havingbeen broken off. More specifically, the present invention co'ntemplates,as means for operating the gate, a series motor supplemented by a shuntfield energized from a local battery and energized between the two andthe eighty seven degree position of the mechanism.

Other objects, purposes and characteristic features of the presentinvention will be pointed out in the following specification and will inpart be obvious from the accompanying drawing in which:

Fig. 1 shows a highway which crosses a railroad track and which'highwayis provided with electrically operated crossing gates embodying thepresent invention, the mechanical and electrical apparatus of only oneof these crossing gates being shown; and

Fig. 2 shows a modification of the invention shown in Fig. 1.

Gate operating structure Referring to the drawing the railroad trackillustrated is divided by insulating joints i into track circuits, eachtrack circuit of which energizes one of the coils of the interlockingrelay E. This interlocking relay R is preferably of the constructionshown ineither the patent to Field No. 1,824,131 or in the patent toHenry et al. No. 1,969,075. This interlocking relay R through frontcontacts 2 and 3 included in series controls the gate operatingmechanism. Each of the crossing gates O and P conventionally shownadjacent the highway comprises a gate, such as plate P, having fastenedthereto a gate arm l0 and a counterweight II. In practice thiscounterweight H is so located and of such weight that it will greatlyaid in moving the gate ill to its clear position, but also of suchweight that upon release of all extraneous forces the gate willgravitate to its horizontal stop position. This gate plate P is fastenedto a main shaft [2, driven by the series motor M including a seriesfield F supplemented at times by the shunt field S through the medium ofgears l3, l4, l5, l6 and I1. series motor M becomes a compound motorwhen the shunt field is also energized. To the motor shaft 20 are keyed,but freely slidable, clutch plates 2i, of which only one has beenillustrated, which clutch plates are pressed toward each other throughthe medium of a coil spring 22 acting against the nut on the end of theshaft 20, and between these clutch plates 2! and freely rotatable on theshaft 20 is a clutch Wheel 23. It is thus seen that this clutch wheel 23is frictionhold-clear mechanism HC is energized, as shown,-

the clutch wheel 23 which tends to rotate counter-clockwise is locked inits then position by a locking pawl 25. This locking pawl 25 is slidablysupported in one of the links of a toggle mechanism through the mediumof three pins 26, 21 and 28 passing through the plates 29 and 30 of thislink of the toggle mechanism, this locking pawl being biased into anengaging position by a spring 3|. These plates 29 and 30 are pivoted asby a pin 32 to a stationary lug 33. The lower end of these plates arepivoted, as by a pin 36 passing through the vertical arm 36 of the anglelever 353B, this angle lever 3536 being pivoted to stationary lugsthrough the medium of a pin 31.

This toggle mechanism is normally held in its effective lockingposition, as illustrated, by an electro-magnet including high resistancecoils H and low resistance coils L. Upon deenergization of the magnet HCthe weight of the armature d2 in addition to the force exerted on thepawl 25 by the clutch wheel 23 causes the pawl 25 to release. Thiselectro-magnet includes the usual back yoke 40, cores 4| and armature42. This electro-magnet when deenergized causes the angle lever 35-36 toassume an abnormal position, where the stop pin 43 engages a stop plate4%, such that the locking pawl 25 no longer engages between the lugs onthe clutch wheel 23. This electro-magnet is so constructed that if thehigh resistance coilsH and the low resistance coils L are connectedinseries and energized by the source of direct current illustrated by thelegends and there will be insufiicient fiux to operate the armature 42of the hold-clear mechanism EC to its locking position. If, however,only the low resistance coils L are connected across this source ofcurrent the armature 42 will be operated to its attracted position,thereby operating the locking pawl 25 to a position to lock the clutchwheel 23. This electro-magnet will, however, maintain its armature 42 inits attracted position, if once lifted to this position, by the fluxemitted when the high resistance coils H and the low resistance coils Lare connected in series across this source of current.

The shaft 45 illustrated by dotted lines is pro- This vided with fourpairs of contacts 4341, 48-49, 505I and 52-53. This shaft 45 is drivenin accordance with the rotation of the shaft I2 through the medium oftwo gear sectors 56 and 51. In order to provide 'electro-dynamicsnubbing through the medium of the motor M a snubbing relay SR has alsobeen provided. This snubbing relay SR may be of the two winding type asshown in the application of J. C. Lindner Ser. No. 247,587, filedDecember 24, 1938, but as here shown is of the single coils type.

For operation of the mechanism from the clear position to the stopposition the snubbing does not begin until the gate arm has been loweredto the 8'7 degree position where the contacts 5253 close to energize theshunt field S. The magnetism produced in the field poles by the directcurrent flowing in this shunt field winding induces a current in thearmature which by flowing through the snubbing circuit including thesupplemental snubbing relay SSR and the snubbing resistance 87 in serieswill retard the motor M. This fiow of current will of course produceelectro-dynamic braking of motor M. This current fiows through the backcontact 88 of the snubbing relay SR, the relay SSR and through snubbingresistance 81. If now the electro-dynamic snubbing current becomesexcessive possibly be.- cause the gate arm I0 is broken ofi and themechanism is operated from its stop to its clear position by gravitythrough the medium of the counterweight I l at an excessive rate, thesupplemental snubbing relay SSR is picked up and by closing of its frontcontact 89 shunts the snubbing resistance 81. In applicant'sconstruction this desired result has been accomplished by including ashunt field winding S which functions not only when the motor isoperated as a'motor but also when used as a dynamic current generator.When the motor is operated from its local direct current source itoperates as a compound motor so long as the contacts 5253 are closed butoperates as a series motor through the medium of series field Falonelwhen the shunt field winding S is deenergized. 'In other words,the field coils F and S are wound cumulatively.

Operation of system Referring to the drawing, let us assume that thereis a train approaching the highway and that as a result of this trainone of the coils of the interlocking relay R is deenergized, therebyopening the circuit including the high resistance coils H and the low'resistance coils L of the holdclear magnet in series. Deenergization ofthe hold-clear magnet causes the armature 42 to drop thereby causing thelocking pawl 25 to be moved to the left out of engagement with the slipclutch wheel 23. By reason of the weight of the crossing gate Ill overthat of its counterweight II, this crossing gate will gravitate towardthe horizontal position and in so doing will rotate the armature A ofthe motor M in the opposite direction from that in which the motor iselectrically operated. By reason of the closure of the circuit for theshunt 'field S when the gate it comes below the 87 degree position avoltage will be built up in the armature A which will create a currentin the snubbing circuit including the armature A, the back contact 88 ofthe snubbing relay SR, the winding of the supplemental snubbing relaySSR and the snubbing resistance 81 in series. This strong magnetic fieldproduced by the field coils S will of course set up a large currentthrough the snubbing circuit just traced, but this current willordinarily not be strong enough to pick up the supplemental snubbingrelay SSR. If the prevailing wind should be in a direction to aid thereturn of the gate additional dynamic braking current will flow due tothe slight increase in the motor speed thereby causing the supplementalsnubbing relay SSR to pick up and shunt the snubbing resistance 8.1.This will, of course, further increase the braking.

Let us now assume that the approaching train has passed the crossing andthat the interlocking relay R is again energized. Energization 01' thisrelay R causes closing of its open contact 2 or 3 thereby closing acircuit through the series motor M, which may be traced from theterminal of a suitable source of direct current, front con- I tacts 2and 3 of the relay R, contacts-4H1 of multiple path includes thesupplemental snubbing relay SSR, and the snubbing resistance 81 inseries. As the motor M operates it turns the" gear sector 51 in aclockwise direction and when it has operated through an angle of 85degrees the contacts 48-49 are closed and when it has reached the 8'7degree position the contacts are closed. Closure of the contacts 48-49completes a circuit from the terminal through contacts 2 and 3 of relayR, contacts 4641 and contacts 4849 of the operating mechanism, throughthe low resistance winding L of the hold-clear magnet, as a result ofwhich this hold-clear magnet is energized to an extent to pick upitsarmature 42. After three additional degrees of operation of the crossinggate I0, namely, when it has been operated to the 88 degree positionfrom its horizontal position,

the contacts 48-41 of the operating mechanism open, thereby removing theshunt which had been established around the high resistance coils H ofthe hold-clear magnet by the contacts 46-41, 48-49 and 505l in series,as a result of which the high resistance coils H and the low resistancecoils L of this hold-clear magnet are connected in series through acircuit including front contacts 2 and 3 of the relay R and contacts50-5! in series. This circuit by reason of the high resistance of thecoils H draws very little current but at the same time is able tomaintain the armature 42 in its raised position.

When the armature 42 of the hold-clear mechanism was actuated to itsattracted position the locking pawl 25 of course engaged the frictionwheel 23 of the friction slip clutch as a result of which a brakingaction is applied to the motor M. The slipping between the frictionwheel 23 and the clutch plates 2| will soon bring the motor M to a stop.

In order to prevent the crossing gate from being operated and heldbeyond the 91 degree position the contacts ill-5| have been made soshort as to be closed only between the 87 degree and the 91 degreeposition. It thus follows that if the gate is operated beyond the 91degree position the hold-clear magnet will be deenergized by the openingof the contacts ill-5|. If the gate now settles back below the 91 degreeposition and the contacts li05l reclose the circuit for the hold-clearmagnet its armature 42 will not be picked up, because it is incapable ofbeing picked up by a circuit including the high resistance coils H andthe low resistance coils L in series. The gate will thus be returned alittle further and when it reaches the 88 degree position and thecontacts 48-41 of the operating mechanism reclose, the circuitsreenergizing the motor M and for shunting the high resistance coils H ofthe hold-clear magnet are closed so that this holdclear magnet will bepicked up through its low resistance coils L The motor M is howeverstill energized to move the mechanism toward the clear position and willafter a short time open the contacts 49-41, resulting in the highresistance coils H being included unshunted in series with the lowresistance coils L.

Let us now assume that the crossing gate is in its horizontal stopposition because one or the other of the contacts 2 or 3 is open, andlet us further assume that an automobile was operated against the gatearm l0 and broke it on near the plate P. Under this condition thecounterweight H produces a very large torque in a counterclockwisedirection in the shaft l2, thereby causing the mechanism to move veryquickly toward its clear position. As the mechanism reaches the 2 degreepositiqnjhe-contacts 52'53 close resulting in tlie"'energizationof theshunt field S for the motor M. The magnetic field produced by the shuntwinding S is very strong and induces in the armature A a direct currentvoltage of substantial value. As a result of the voltage induced in thearmature A snubbing current flows ,through the back contact 88 of thesnubbing relay resistance 81 back'to the armature A. Because thissnubbing current is considerably in excess of the normal snubbingcurrent value the supplemental snubbing relay SSR is picked up, causingits front contact 89 to shunt the snubbing resistance 81. The resistanceof the snubbing circuit has now been greatly decreased resulting intheflow of a heavier snubbing current and resulting in more pronouncedsnubbing action and greater retardation for the armature of the motor Adriven by the gravity through the medium of the counterweight ll. 1

It is thus seen that provision has been made through the medium of theshunt field S, which is energized only between the 2 degree and 87degree position of the plate P to which the gate arm I8 is normallybolted, to cause the motor M to be snubbed irrespective of the directionin which its armature is operated. Provision has also been made by theemployment of the supplemental relay SSR for reducing the resistance ofthe snubbing circuit when the extraneous forces.

which operate the armature A are beyond those present when the gate armI 0 gravitates from its clear to its stop position. In other words, thesupplemental snubbing relay SSR may through the medium of its frontcontact 89 shunt the snubbing resistance 81 and this takes place whenthe dynamic braking action necessary is greater than what is normallyrequired.

Even though provision has been made for producing special and heavysnubbing action when the gate arm I 0 has been broken off to prevent thegate moving to its clear position at such a speed as to break itsmechanism, it becomes apparent that if the gate arm l0 should be brokenoiT just at the instant that the open contacts 2 or 3 of the inerlockingrelay R became closed there is a possibility that sufflcient currentwould fiow through the motor M and the snubbing relay SR that the backcontact 88 of the snubbing relay would be open and therefore no snubbingcould take place. In Order to avoid this coincidence of closure of thecontacts 2 or 3 and the breaking of the arm l causing excessive speedmovement of the mechanism to its clear position, it is proposed toemploy a test link I00 constructed of brittle metal such as lead, castiron, or zinc so secured to the gate arm I!) that breakage of the gatearm will also result in the breakage of the link I00 and breakage of thecircuit including this link H in series with the contacts 2 and 3 of therelay R, all as shown in Fig. 2 of the drawing. This construction willassure that breakage of the gate arm will result in. properelectro-dynamic braking of the motor.

One of the reasons for providing the supplemental snubbing relay is toincrease the snubbing resistance under normal operating conditions sothat the gate will not gravitate to its stop position too slowly. Also,if desired some resistance external of the relay SSR which is notshuntable by the contact 89 may be added.

Applicants have thus shown and described an electrically operatedcrossing gate embodying certain new features including novelelectro-dynamic braking means, these means including a shunt field whichis directly energized from a local source of direct current betweencertain degrees of operation of the crossing gate, so that the motor foroperating such crossing gate 'may be electro-dynamically snubbed foreither direction of rotation of its armature, and although thesefeatures of construction have been rather specifically illustrated inthe drawing, it is desired to be understood that this has been done tofacilitate description of the invention rather thanto illustrate itsscope or the particular construction and it is further to be understoodthat suchchanges as are within the scope of the appended claims may bemade to the present invention without departing from its spirit orscope.

What we claim as new is:

1. In an electrically operated crossing gate, the combination with acrossing gate pivoted to a stationary support and partiallycounterbalanced so as to be biased toward its substantially horizontalstop position only to an extent to move to and return its operatingmechanism to such stop position, a direct current motor and reductiongearing for operating said operating mechanism and in turn said gate toits substantially vertical clear position, a shaft for said motor, afriction slip clutch on said shaft, a hold-clear mechanism effective toengage said clutch to render it effective when said motor is energizedand said gate is in its clear position, a check link on said gateelectrically broken when said gate is broken offhand a snubbing circuitincluding the armature of said motor effective to brake said motor whenrunning in either direction, and a shunt field circuit for said motorenergized from a local source and closed only during an intermediateposition of such operating mechanism for inducing a voltage in saidarmature during snubbing action.

2. In an electrically operated crossing gate, the combination with acrossing gate pivoted to a stationary support and partiallycounterbalanced so as to be biased toward its substantially horizontalstop position only to an extent to move to and return its operatingmechanism to such stop position, operating mechanism including a directcurrent series motor and reduction gearingforoperating said gate to itssubstantially vertical clear position, a shaft for said motor, afriction slip clutch on said shaft, a hold-clear mechanism effectivetoengage said clutch to render it effective when said motor is energizedand said gate is in its clear position, a shunt field winding for saidmotor, a snubbing circuit for the arma- "ture of said motor closed whensaid motor is disconnected from said source of direct current andeffective to electro-dynamically brake said motor when a field circuitincluding said shunt field winding is closed irrespective of thedirection of rotation of said motor, and contacts for controlling saidfield circuit closed only when said operating mechanism assumes anintermediate position. 1

3. In an electric motor operated crossing gate, the combination with agate fastened to a horizontal shaft and partly counterbalanced so thatthe shaft is biased to a substantially horizontal stop position but isvery strongly biased to a substantially vertical clear position if thegate is broken off, a gear train, a series motor including an armatureand a series field in series for operating said shaft to a clearposition through the medium of said gear train, a snubbing circuitincluding in series said armature and a snubbing resistance forelectro-dynamically braking said motor when operated in eitherdirection, a shunt field for said motor so wound that the magnetism fromsaid series field and said shunt field when energized is cumulative, andmeans for energiz ing said shunt field including a localsource of directcurrent and contacts closed only when said horizontal shaft assumes aposition between said clear and said stop position.

. 4. In an electric motor operated crossing gate, the combination with agate fastenedto a horizontal shaft and partly counterbalanced so thatthe shaft is biased substantially to a stop position but is verystrongly biased to a substantially Vertical clear position if the gateis broken oif, a gear train, a series motor for operating said shaft toa clear position through the medium of said gear train, a clutch wheelfrictionally connected to the shaft of said series motor; a holdclearmagnet having a high resistance coil and a low resistance coil and whichif in an active condition locks said clutch wheel; a control relay; afirst contact, a second contact and a third contact controlled by saidshaft of which the first'contact opens when said shaft assumes apredetermined position and of which the second contact and third contactclose when said shaft has almost reached said predetermined position; anoperating circuit for said motor including a contact of said controlrelay, a source of current and said first contact; a circuit for saidlow resistance coil including in series said source, a contact of saidcontrol relay said first contact and said second contact in series; acircuit for said high resistance coil and said low resistance coil inseries including a contact of said control relay, said source and saidthird contact; a-snubbing circuit for said motor including in series thearmature of said motor and a snubbing resistance; a shunt field for saidmotor, and means for energizing said shunt field when said horizontalshaft assumes a position between said clear position and said stopposition, whereby. said motor may be dynamically braked irrespective ofthe direction of operation of said armature.

5. In an electric motor operated crossing gate, the combination with agate fastened to a horizontal shaft and partly counterbalanced so thatthe shaft is biased to a substantially horizontal stop position but isvery strongly biased to a substantially vertical clear position if thegate is broken off; a gear train, a motor for operating said horizontalshaft through. the medium of said gear train from the stop to the clearposition, a shunt field winding for said motor deenergized at and nearthe stop position and the clear position of said shaft and energized forall circuit for said motor closed when the control circuit for saidmotor is open and including in series the armature of said motor, arelay and a snubbing resistance whereby said armature may be dynamicallybraked irespective of the direction of rotation ,of said armature solong as said shunt field is closed, and a front contact on said relayfor shunting said snubbing resistance whereby the resistance of thesnubbing circuit is reduced if the snubbing current is large enough topick up the armature of said relay.

6. In an electric motor operated crossing gate, the combination with agate fastened to a horizontal shaft and partly counterbalanced so thatthe shaft is biased to a substantially horizontal stop position but isvery strongly biased to a substantially clear position if the gate isbroken off, a gear train; a snubbing relay; a motor for operating saidhorizontal shaft through the me-' dium of said gear train from the stopto the clear position through a control circuit including a series fieldof said motor, said snubbing relay, the armature of said motor and asource of direct current in series; a shunt field winding for said 40motor deenergized at and near the stop position and the clear positionof said shaft and energized from said source for all intermediatepositions of said shaft and in a direction to produce magnetismcumulatively withrespect to the magnetism produced by said series fieldwhen energized by said control circuit; and a snubbing circuit includinga back contact of said snubbing relay, said armature and a snubbingresistance in series. 7. In an electric motor operated crossing gate,

the combination with a gate fastened to a horizontal shaft and partlycounterbalanced so that the shaft is biased to a substantiallyhorizontal stop position but is very strongly biased to a substantiallyclear position if the gate is broken ofi,

a gear train; a snubbing relay; a motor for operating said horizontalshaft through the medium of said gear train from the stop to the clearposition through a control circuit including a series field of saidmotor, said snubbing relay, the armature of said motor and a source ofdirect current in series; a shunt field winding for said motordeenergized at and near the stop position and the clear position of saidshaft and energized from said source for all intermediate positions ofsaid shaft and in a direction to pro-' duce magnetism cumulatively withrespect to the magnetism produced by said series field when energized bysaid control circuit; a snubbing 7O circuit including aback contact ofsaid snubbing relay, said armature, a supplemental snubbing relay and asnubbing resistance in series; and a front contact on said supplementalsnubbing relay which if closed shunts said snubbing resistance.

intermediate positions of said shaft, a snubbing 8. In an electricallyoperated crossing gate, the combination with a gate arm which may assumea substantially vertical clear position and a substantially horizontalstop position, a counterweight biasing said gate from its clear positionand partly counterbalancing said gate between the stop position andanintermediate position, a motor including an armature and a field coil inseries for operating said arm from a stop to a clear position, asnubbing relay; an operating circuit for said motor including saidarmature, said field coil, a source of current and said snubbing relayin series; a shunt field coil for said motor; a circuit for energizingsaid shunt field coil including said source of current closed forsubstantially all positions of said gate arm except the stop and theclear position, said shunt field coil being poled to produce magnetismcumulatively with said series coil; and a snubbing circuit for saidmotor including said armature, a back contact of said snubbing relay anda snubbing resistance in series.

9. In an electrically operated crossing gate, the combination with agate arm which may assume a substantially vertical clear position and asubstantially horizontal stop position, a counterweight'biasing saidgate from its clear position and partly counterbalancing said gatebetween the stop position'and an intermediate position, a motorincluding an armature and a field coil in series for operating said armfrom a stop to a clear position, a snubbing relay; an operating circuitfor said motor including said armature, said field coil, a source ofcurrent and said snubbing relay in series; a shunt field coil for saidmotor; a circuit for energizing said shunt fieldcoil including saidsource of current closed for substantially all positions of said gatearm except the stop and the clear position, said shunt field coil beingpoled to produce magnetism cumulatively with said series coil; asnubbing circuit for said motor including said armature, a back contactof said snubbing relay and a snubbing resistance in series; asupplemental snub-' bing relayy and a front contact on said supplemental snubbing relay included in multiple with said snubbingresistance, said supplemental snubbing relay being constructed so as notto pick up for snubbing current of normal value but which will pick upand reduce the resistance of the snubbing circuit when the snubbingcurrent becomes excessive.

10. In an electrically operated crossing gate, the combination with agate arm which may assume a substantially vertical clear position. and asubstantially horizontal stop position, a counterweight biasing saidgate from its clear position and partly counterbalancing said gatebetween the stop position and an intermediate position, a motorincluding an armature and a field coil in series for operating said armfrom a stop to a clear position, a snubbing relay; an operating circuitfor said motor including said arma ture, said field coil, a source ofcurrent and said snubbing relay in series; a shunt field coil for saidmotor; a circuit for energizing said shunt field coil including saidsource of current closed for'substantially all positions of said gatearm except the stop and the clear position, said shunt field coil beingpoled to produce magnetism cumulatively with said series coil; asnubbing circuit for said motor including said armature, a back contactof said snubbing relay and a snubbing resistance in series; and meansfor opening said operating circuit at another point if said gate arm isbroken oiT.

11. In an electrically operated crossing gate, the combination with agate arm which may assume a substantially vertical clear position and asubstantially horizontal stop position, a counterweight biasing saidgate from its clear position and partly counterbalancing said gatebetween the stop position and an intermediate position, a motorincluding an armature and a field coil in series for operating said armfrom a stop to a clear position, a snubbing relay; an operating circuitfor said motor including said armature, said field coil, a source ofcurrent and said snubbing relay in series; a shunt field coil for saidmotor; a circuit for energizing said shunt field coil including saidsource of current closed for substantially all positions of said gatearm except the stop and the clear position, said shunt field coil beingpoled to produce magnetism cumulatively with said series coil; asnubbing circuit for said motor including said armature, a back contactof said snubbing relay and a snubbing resistance in series; asupplemental snubbing relay; a front contact on said supplementalsnubbing relay included in multiple with said snubbing resistance, saidsupplemental snubbing relay being constructed so as not'to pick up forsnubbing current of normal value but which will pick up and reduce theresistance of the snubbing circuit whenthe snubbing current becomesexcessive; and means for opening said operating circuit at another pointif said gate arm is broken oil.

12. In an electrically operated crossing gate,

the combination with a gate arm which may assume a substantiallyvertical clear position and a substantially horizontal stop position, acounterweight biasing said gate from its clear position and partlycounterbalancing said gate between the stop position and an intermediateposition, a motor including an armature and a field coil in series foroperating said arm from a stop to a clear position, a snubbing relay; anoperating circuit for said motor including said armature, said fieldcoil, a source of current and said snubbing relay in series; hold-clearmeans controlled by a circuit in multiple with said operating circuitfor holding said gate arm in its clear position; a shunt field coil forsaid motor; a circuit for energizing said shunt field coil includingsaid source of current closed for substantially all positions of saidgate arm except the stop and the clear position, said shunt field coilbeing poled to produce magnetism cumulatively with said series coil; asnubbing circuit for said motor including said armature, a back contactof said snubbing relay and a snubbing resistance in series; asupplemental snubbing relay; and a front contact on said supplementalsnubbing relay included in multiple with said snubbing resistance, saidsupplemental snubbing relay being constructed so asnot to pick up forsnubbing current of normal value but which will pick up and reduce theresistance of the snubbing circuit when the snubbing current becomesexcessive.

13. In an electrically operated crossing gate, the combination with agate arm which may assume a substantially vertical clear position and asubstantially horizontal stop position, a counterweight biasing saidgate from its clear position and partly counterbalancing said gatebetween the stop position and an intermediate position, a motorincluding an armature and a field coil in series for operating said armfrom a stop to a clear position, a snubbing relay; an operating circuitfor said motor including said armature, said field coil, a source ofcurrent and said snubbing relay in series; hold-clear means controlledby a circuit in multiple with said operating circuit for holding saidgate arm in its clear position; a shunt field coil for said motor; acircuit for energizing said shunt field coil including said source ofcurrent closed for substantially all positions of said gate arm exceptthe stop and the clear position, said shunt field coil being poled toproduce magnetism cumulatively with said series coil; a snubbing circuitfor said motor including said armature, a back contact of said snubbingrelay and a snubbing resistance in series; and means for opening saidoperating circuit at another point if said gate arm is broken off. I

14. In an electrically operated crossing gate, the combination with agate arm which may assume a substantially vertical clear position and asubstantially horizontal stop position, a counterweight biasing saidgate from its clear position and partly counterbalancing said gatebetween the stop position and an intermediate position, a motorincluding an armature and a field coil in series for operating said armfrom a stop to a clear position, a snubbing relay; an operating circuitforsaid motor including said armature, said field coil, a source ofcurrent and said snubbing relay in series; hold-clear means controlledby a circuit in multiple with said operating circuit for holding saidgate arm in its clear position; a shunt field coil for said motor; acircuit for energizing said shunt field coil including said source ofcurrent closed for substantially all positions of said gate arm exceptthe stop and the clear position, said shunt field coil being poled toproduce magnetism cumulatively with said series coil; a snubbing circuitfor said motor including said armature, a back contact of said snubbingrelay and a snubbing resistance in series; a supplemental snubbingrelay; a, front contact on said supplemental snubbing relay included inmultiple with said snubbing resistance, said supplemental snubbing relaybeing constructed so as not to pick up for snubbing current of normalvalue but which will pick up and reduce the resistance of the snubbingcircuit when the snubbing current becomes excessive; and means foropening said. operating circuit at another point if said gate arm isbroken 01$.

15. In an electrically operated crossing gate, in combination, a gatemovable to a stop and a clear position, an electrical motor connected tothe gate, means partly counterbalancing the gate so that the gate andits operating means is biased to move to its stop position, a local,separately excited field winding on the motor, and a low resistancesnubbing circuit connected to the motor and closed when the motor ismechanically driven in the direction corresponding to movement of thegate to clear position.

16. In an electrically operated crossing gate, in combination, a gatemovable toa stop and a clear position, an electrical motor connected tothe gate, means partly counterbalancing the gate so that the gate andits operating means is biased to move to its stop position, a local,separately excited field winding on the motor, a low resistance snubbingcircuit connected to the motor and closed when the motor is mechanicallydriven in the direction corresponding to movement of the gate to clearposition, and means for reducing the resistance in the snubbing circuitupon the snubbing current exceeding a predetermined value, whereby tovary the degree of snubbing.

17. In an electrically operated crossing gate, in combination, a gatemovable to a stop and a clear position, an electrical motor having aseries field winding and connected to the gate, means partlypounterbalancing, the gate so that the gate and its operating means isbiased to move to its stop position, a local, separately excited fieldwinding on the motor and poled in the same direction as theserleswinding, and a low resistance snubbing circuit connected to the motorand closed whenthe motor is mechanically driven in the directioncorresponding to movement oi. the gate to clear position.

18. In an electrically operated crossing gate, in combination, a gatemovable to a stop and a clear position, an electrical motor having aseries field winding and connected to the gate, means partlycounterbalancing the gate so that the gate and its operating means isbiased to move to its stop position, a local, separately excited fieldwinding on the motor and poled in the same direction as the serieswinding, a low resistance snubbing circuit connected to the-motor andclosed when the motor is mechanically driven in the directioncorresponding to movement of the gate to clear position, and means forreducing the resistance in the snubbing circuit upon the snubbingcurrent exceeding a predetermined value, whereby to vary the degree oisnubbing.

wm'nmon K. HOWE. JOHN c. LINDNER.

